Two considerations present themselves with regard to the necessary relation of species to time if the theory of “Natural Selection” is valid and sufficient.

The first is with regard to the evidences of the past existence of intermediate forms, their duration and succession.

The second is with regard to the total amount of time required for the evolution of all organic forms from a few original ones, and the bearing of other sciences on this question of time.

As to the first consideration, evidence is as yet against the modification of species by “Natural Selection” alone, because not only are minutely transitional forms generally absent, but they are absent in cases where we might certainly a priori have expected them to be present.

Now it has been said: “If Mr. Darwin's theory be true, the number of varieties differing one from another a very little must have been indefinitely great, so great indeed as probably far to exceed the number of individuals which have existed of any one variety. If this be true, it would be more probable that no two specimens preserved as fossils should be of one variety than that we should find a great many specimens collected from a very few varieties, provided, of course, the chances of preservation are equal for all individuals.”